Loud bang near water heater when Sloan toilet is flushed.

[Joshmee123]

Hello to whoever can help me.

I'm trying to stop a noise issue in a busy 20 unit salon located in a mall. Every time a Sloan toilet is flushed (3 of them) there is a loud water hammer bang in the ceiling near the commercial cyclone heater. I've installed arrestors on the riser 90s in the drop ceiling above but no luck. The pressure reads 65 psi and there is an expansion tank. The system isn't closed with the rest of the mall and there is no regulator.

If someone can help me out I'd appreciate it. Thanks!!

Josh

 

[Reach4]

I am not a plumber. I would consider putting a well pressure tank on the supply line to the toilets. I might put a check valve before that. If you want to discuss sizes or what precharge to use, say so.

 

[Sponsor]

 

[WorthFlorida]

Is the noise at the start of the flush or when it stops. I assume these are non tank toilets? Have you checked the pressure in the expansion tank? With a pin open the Schrader valve to be sure no water spits out. If there is a lot of water the bladder is bad.

On sloan valves you can use the shut off valve to close off some of the water flow. It should reduce the quick blast of water. Close it down until it will no longer flush then open it slowly until you get a good flush but hopefully not fully open.

If a hot water side of a faucet is quickly shut off, is there any noise? Any idea when the problem started?

 

[Joshmee123]

I am not a plumber. I would consider putting a well pressure tank on the supply line to the toilets. I might put a check valve before that. If you want to discuss sizes or what precharge to use, say so.

Yes, I'll take the details as far as precharge and size

 

[Jadnashua]

While looking in the area, have someone flush a toilet and see if you can notice the pipe moving. If you can, a pipe clamp might solve it if it's literally hitting something.

Hammer arresters work best when located as close to the offending quick-acting valve as possible. Because that type of toilet uses a fairly large supply pipe, an arrester designed for 1/2" pipe probably won't have enough volume to do much.

 

[Reach4]

Yes, I'll take the details as far as precharge and size

I am thinking that each toilet uses a little less than 2 gallons per flush. Lets say two may be flushed at the same time. Each tank can hold about 1/4 of the volume in water. I am thinking that a 20 gallon tank would be at the upper limit of what I am thinking, and that 10 may be enough. https://www.supplyhouse.com/Amtrol-...20-Gal-WELL-X-TROL-Well-Tank-w-Durabase-Stand would be a high-quality 20 gallon tank that is in stock.

Ideally the 1 inch NPT connection at the tank would connect to a tee. One side would receive supply water, and the other side would feed the three toilets.

For air precharge, I think I would go about 45 or 50 psi, so they would have a lot of water in them normally. That water could supply the toilets pretty quickly. Air precharge is set and mesured while the water pressure is zero. Standard Schrader valve, such as on a tire.

I am also thinking I would put a spring loaded check valve in series with the feed to the tee. The size would not be critical, since the tank will recharge between flushes. https://www.supplyhouse.com/Spring-Loaded-Check-Valves-24911000
I am not sure that the check valve is important. So if it is easy enough to leave out initially but add later, that would be worth considering.

I am not a pro. Let's invite others to suggest a downside or improvement to this idea.

 

[Jadnashua]

It appears that a triple filtering diaphragm kit from Zurn may fit the Sloan valve. https://www.supplyhouse.com/Zurn-P6...Diaphragm-Repair-Kit-for-1-1-GPF-Flush-Valves It slows the shutoff of the valve which stops the rapid off which causes the hammering. Also, there's a small orifice in the Sloan valve that, depending on the water quality, can affect how the valve shuts off. Cleaning that may help.

I do not know for sure the part is interchangeable, but your supplier should know. Might be worth trying one to see if it solves your problem.

 

[Jeff H Young]

The expansion tank idea might work water hammers are frustrating . So you have 65 psi but your delivery in volume could be poor causing excessive pressure drop so the rush of water causes problem . the expansion tank storing the water could keep from getting such a change in pressure plus the added benefit of absorbing the shock. I dont think this is a conventional fix but I wouldnt be suprised to see this work . I cant stick my neck out there and suggest due to the expence but generaly it sounds feasable.
I met a rep with sloan at a trade show the guy was such a wiz , Maybe a diaphram change or a call to them in order

 

[hj]

If you put a gauge on the main, you will probably discover that when the flushometer activates the pressure drops to ZERO and immediately "pins" the gauge and the hammer occurs. A small "diaphragm" pressure tank will stabilize the pressure until the water in the line overcomes its inertia and starts moving.